title: RisedronatE and ALendronate Intervention over Three Years (REALITY): minimal differences in fracture risk reduction.
abstract: CONCLUSIONS
  The comparative effectiveness of alendronate and risedronate has received limited evaluation. Among 19,063 new users of bisphosphonates, risedronate users had a higher relative rate of hip fracture compared to alendronate users, but the difference in absolute fracture rate was small. We conclude that the agents have comparable efficacy.
  
  
  BACKGROUND
  Bisphosphonates differ in their in vitro potency, avidity for bone, and rapidity of onset in clinical trials. To address potential differences between bisphosphonates in comparative effectiveness, we compared new users of alendronate and risedronate to determine if there were differences in the risk of clinical fractures at 1 year and beyond.
  
  
  METHODS
  Using claims data from a U.S. health care organization, we identified new, adherent users of weekly alendronate or risedronate and assessed subsequent fractures. We calculated fracture incidence rate differences and ratios between the two agents.
  
  
  RESULTS
  There were no significant differences in fracture rates between alendronate users (n = 12,956) and risedronate users (n = 6,107) at 1 year. Using all available data, the rate of hip fracture was higher among risedronate users compared to alendronate users (absolute rate difference approximately five per 1,000 person-years). Risedronate users had a higher relative rate (RR) of hip fracture (RR = 1.77, 95% CI 1.15-2.74) and similar rates of clinical vertebral and nonvertebral fractures compared to alendronate users.
  
  
  CONCLUSIONS
  The absolute rate of clinical fractures among alendronate and risedronate users was similar both at 1 year and beyond, suggesting comparable effectiveness between agents.
authors.affiliation: Center for Education and Research on Therapeutics, University of Alabama at Birmingham, Birmingham, AL, USA. jcurtis@uab.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Curtis
authors.forename: A O
authors.initials: AO
authors.lastname: Westfall
authors.forename: H
authors.initials: H
authors.lastname: Cheng
authors.forename: K G
authors.initials: KG
authors.lastname: Saag
authors.forename: E
authors.initials: E
authors.lastname: Delzell
mesh_terms: D000368:Aged; D019386:Alendronate / Q000627:therapeutic use*; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D004164:Diphosphonates / Q000627:therapeutic use; D012968:Etidronic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006620:Hip Fractures / Q000188:drug therapy / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D010024:Osteoporosis / Q000150:complications / Q000188:drug therapy*; D017698:Postmenopause; D016032:Randomized Controlled Trials as Topic; D000068296:Risedronic Acid; D040242:Risk Reduction Behavior; D016103:Spinal Fractures / Q000188:drug therapy / Q000517:prevention & control*; D016896:Treatment Outcome; D016903:Drug Monitoring
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate